Figure 3. Inhibitory effects of different antioxidants on induced VEGF secretion.

In A, HESC were treated overnight with RA + TPA, H₂O₂+ TPA, or vehicle control (Con) in the absence or presence of NAC (2.5 mm), PEG-catalase (100 U ml⁻¹), or unconjugated PEG (18 μm, as a control for PEG-catalase) as indicated. Results show that NAC inhibited secretion of VEGF induced by both combination treatments while PEG-catalase inhibited secretion induced by H₂O₂+ TPA but not that induced by RA + TPA. *Significant decrease from similarly treated cultures in the absence of antioxidant. B shows dose-dependent inhibition by GSH-MEE on VEGF secretion induced by both RA + TPA and H₂O₂+ TPA. Significant inhibition was seen at all GSH-MEE concentrations tested. Concentrations of RA, H₂O₂ and TPA in all experiments were as shown in the legend to Fig. 1.